package com.wl.shixun1.mymvc;

public interface Num {
    public Num add(Num num);
    public Num sub(Num num);
    public Num mul(Num num);
    public Num div(Num num);
    public String draw1();
    

    public default Num calculateExpression(Num num2, Num num3, String op1, String op2) {
        return null;
    }
}